1. Field of the Invention
The present invention relates to an adsorptive type refrigeration apparatus utilizing adsorbent such as silica gel or zeolite to be employed as a portion of for example an air-conditioning apparatus.
2. Description of the Related Art
As shown in FIG. 2, an adsorptive type refrigeration apparatus according to the prior art is structured from a pair (two) of adsorbers 1 and 2 internally filled with an adsorbent such as silica gel or zeolite and disposed in parallel, an evaporator 3 which cools air within a room by a refrigerant such as circulating water and discharges cooled air, a condenser 4 which cools and causes liquefaction of refrigerant by external air, a four-way valve 6 or three-way valves 6' and 6" to switch passages and disposed intermediately in piping which connects between these adsorbers or connects these to an external device, and furthermore a device such as a pump 7 which causes refrigerant to circulate. The adsorber 1 is provided with a cooling pipe 1' and heating pipe 1", and the adsorber 2 is similarly provided with a cooling pipe 2' and heating pipe 2".
FIG. 2 indicates a case (operation state) where the adsorption device 1 on the left-hand side is in a state of an adsorption process wherein adsorbent in an interior of the adsorber 1 has adsorbed refrigerant vapor (steam) and, along with this, the adsorber 2 of the right-hand side is an a state of a desorption (release) process wherein adsorbent in an interior of the adsorber 2 has desorbed and discharged refrigerant vapor (steam). The several valves 6, 6', and 6" are switched and operated by a controller not illustrated so that the adsorber 1 and adsorber 2 alternatingly repeat the adsorption process and desorption process and, together with this, each assumes the process which is the opposite of the other.
Hot water of for example 100.degree. C. is supplied as a heating fluid, and water of for example 40.degree. C. is supplied as a cooling fluid. In the state indicated in FIG. 2, adsorbent within the adsorber 1 has discharged water vapor in the previous desorption process and so its amount of water content has been reduced and its amount adsorbed (this is indicated by percentage i.e., this means moisture-adsorption ratio) has dropped, and its capacity to adsorb water vapor has recovered (regenerated). Because of this, heat is generated and temperature of the adsorber 1 interior rises when air is cooled in the evaporator 3. Since the capacity of the adsorbent to adsorb water vapor declines, water of for example 40.degree. C. cools the adsorbent by flowing as cooling fluid in the cooling pipe 1' of the adsorber 1. Consequently, the adsorbent adsorbs water until the adsorbent approaches a saturated state at the temperature of 40.degree. C.
In the state shown in FIG. 2, the adsorber 2 simultaneously executes the desorption process. By causing hot water of for example 100.degree. C. to flow as heating fluid in the heating pipe 2" in the desorption process, adsorbent within the adsorber 2 is heated and water absorbed in the previous adsorption process is desorbed (released). Water vapor generated at the time thereof is sent to the condenser 4 and is condensed. Through this, the amount of water content of the adsorbent within the adsorber 2 is reduced, the amount adsorbed drops, and the capacity to adsorb water vapor again recovers (regenerates). Passages are switched by the several valves 6, 6', and 6", and when oppositely to FIG. 2 the adsorber 1 on the left-hand side is placed in a state of the desorption process and, along with this, the adsorber 2 of the right-hand side is placed in a state of the adsorption process, it is possible to cool air to for example approximately 5.degree. C. in the evaporator 3 and cause cooled air to be generated essentially continuously.
In a case where water of 40.degree. C. is used as cooling fluid and hot water of 100.degree. C. is used as heating fluid in an attempt to obtain heat at approximately 5.degree. C. in an adsorptive type refrigeration apparatus by for example silica gel and water in this way, as shown in FIG. 4, the residual amount adsorbed of adsorbent within the adsorber at the time of termination of the desorption process is approximately 4% wt (point A of FIG. 4), and the amount adsorbed of adsorbent within the adsorber at the time of termination of the adsorption process is approximately 7% wt (point B of FIG. 4). Consequently, according to this example, adsorption and desorption comes to be between the amount adsorbed of 4% and 7% and because this difference is merely 3% wt, which is small, it is necessary to fill the adsorbers with a large quantity of adsorbent in order to obtain sufficient refrigeration capacity (cooling capacity).
In this regard, according to the prior art stated in Japanese Patent Application Laid-open No. 5-248727, a method involving boosting the extent of desorption by causing moisture desorbed from adsorbent of one adsorber to be absorbed by the adsorbent of another adsorber is proposed to sufficiently lower an amount adsorbed (quantity) of adsorbent in a desorption process. That is to say, this prior art adopts a structure which makes multiple stages in the adsorber in the desorption process of the adsorber.
According to this method, however, although the amount adsorbed of 4% wt at the time of termination of the desorption process can be further reduced, it cannot be caused to be 0% wt, and even if hypothetically the amount adsorbed could be set to be 0% wt, an effect of reduction is small, and in a case where the adsorbent is silica gel, it cannot be said that an adsorption capacity which is 37% wt at maximum is sufficiently used to advantage. Even in a case where the cooling of 30.degree. C. stated in Japanese Patent Application Laid-open No. 5-248727 is performed, only a amount adsorbed-adsorption ratio of approximately 15% is obtained, and this figure is not even half of the maximum amount adsorbed. When cooling temperature is 40.degree. C., which is even higher, substantially only adsorption of approximately 9% is performed. As a result of this, the amount of adsorbent used becomes large even in this case of the prior art, the volume of an adsorber to contain this becomes large, and sufficient compactness of the adsorptive type refrigeration apparatus becomes difficult.